Method and apparatus for wireless management of articles

ABSTRACT

The present invention is directed to method and apparatus for wireless management of articles. The method is implemented by a master RFID tag. The method includes transmitting at least one first RFID read signal to a plurality of RFID tags local to the master RFID tag and receiving a first RFID response signal from each of the plurality of RFID tags in response to the at least one first RFID read signal. Each of the first RFID response signals comprises an identifier associated with an article. The method further includes maintaining an article record indicating at least one expected article that is to be managed by the master RFID tag and comparing each of the identifiers with the article record in an attempt to compile contextual information associated with the article record. The method further includes transmitting a master signal comprising the contextual information associated with the article record.

RELATED APPLICATIONS

This Application is a Continuation of U.S. patent application Ser. No.11/965,267, filed on Dec. 27, 2007, and entitled “METHOD AND APPARATUSFOR WIRELESS MANAGEMENT OF ARTICLES” which claims the benefit under 35U.S.C. §119(a) to Canadian Patent Application No. 2,572,649 filed onDec. 29, 2006, and entitled “METHOD AND APPARATUS FOR WIRELESSMANAGEMENT OF ARTICLES”. These applications are commonly owned, and areincorporated by reference in their entirety.

FIELD OF THE INVENTION

This invention relates generally to inventory and asset managementsystems and more specifically to a method and apparatus for wirelessmanagement of articles.

BACKGROUND OF THE INVENTION

Inventory and asset systems are rapidly moving towards wireless,electronic management of goods. Data associated with the goods, forexample an identification number, is stored in the memory of anelectronic tag, which is attached to the goods. In some instances, thetags are attached to individual items. In other instances, tags areattached to the cases in which the items are shipped or to the palletson which the cases are stacked. In some instances, cases on a pallet arewrapped in plastic to retain the cases on the pallet, and the tags maybe placed on the plastic rather than the pallet itself. The data storedin the memory may be wirelessly retrieved by placing the tag in theproximity of an electronic tag reader. The electronic tag readerwirelessly retrieves the data by transmitting a read request to the tag,and the tag responds by transmitting the data to the reader.

A Radio Frequency IDentification (RFID) system, composed of RFID tagsand RFID readers, is one example of a wireless electronic tag systembeing used today. Indeed, RFID devices have changed the manner in whichmany companies manage inventory and assets. Further, specificallyrelated to management of inventory, many companies now demand that theirsuppliers place RFID tags on all shipped goods, at the pallet leveland/or the case level and/or the item level or a combination. RFIDtagged goods which arrive at a warehouse are passed by an RFID reader,which wirelessly retrieves the data stored on the RFID tags. In manycases, a company will only pay a supplier for the goods once the RFIDtag has been read, either at the case level or the item level.

An RFID reader requires a period of time to retrieve the data from theRFID tag. When RFID tagged goods arrive at a warehouse, the pallets onwhich the cases are stacked, are generally passed near an RFID reader,often for only a brief period of time. For example, in some instances,the pallet is passed near the RFID reader only while the pallet is beingmoved from one part of the warehouse to another. In some circumstances,the time period that the pallet is in the proximity of the RFID readermay be less than the time required by the RFID reader to retrieve thedata from all the RFID tags on the pallet. Hence, the data received froma given RFID tag may be incomplete, resulting in an inaccurate inventorycount. This may, in turn, lead to an incomplete, disputed or delayedpayment transmitted between various entities involved in the shipment ofthe goods.

There remains a need therefore for an improved method and apparatus forwireless management of articles.

SUMMARY OF THE INVENTION

According to a first broad aspect, the present invention seeks toprovide a method implemented by a master RFID tag. The method comprisestransmitting at least one first RFID read signal to a plurality of RFIDtags local to the master RFID tag and receiving a first RFID responsesignal from each of the plurality of RFID tags in response to the atleast one first RFID read signal. Each of the first RFID responsesignals comprise an identifier associated with an article. The methodfurther comprises maintaining an article record indicating at least oneexpected article that is to be managed by the master RFID tag andidentifying one or more extra articles by identifying a specificidentifier received within the plurality of first RFID response signalsthat lacks a corresponding specific expected article within the articlerecord. Yet further, the method comprises transmitting a master signalcomprising one or more identifiers of the extra articles.

According to a second broad aspect, the present invention seeks toprovide a method implemented by a master RFID tag. The method comprisestransmitting at least one first RFID read signal to a plurality of RFIDtags local to the master RFID tag and receiving a first RFID responsesignal from each of the plurality of RFID tags in response to the atleast one first RFID read signal. Each of the first RFID responsesignals comprise an identifier associated with an article. The methodfurther comprises maintaining an article record indicating at least oneexpected article that is to be managed by the master RFID tag andidentifying one or more missing articles by identifying a specificexpected article within the article record that lacks a correspondingspecific identifier received within the plurality of first RFID responsesignals. Yet further, the method comprises transmitting a master signalcomprising one or more identifiers of the missing articles.

According to a third broad aspect, the present invention seeks toprovide a master RFID tag comprising a first communication unit, amemory unit, a processing unit and a second communication unit. Thefirst communication unit is operative for transmitting at least onefirst RFID read signal to a plurality of RFID tags local to the masterRFID tag and receiving a first RFID response signal from each of theplurality of RFID tags in response to the at least one first RFID readsignal. Each of the first RFID response signals comprise an identifierassociated with an article. The memory unit is operative for storing anarticle record indicating at least one expected article that is to bemanaged by the master RFID tag. The processing unit is operative for atleast one of: identifying one or more extra articles by identifying aspecific identifier received within the plurality of first RFID responsesignals that lacks a corresponding specific expected article within thearticle record and identifying one or more missing articles byidentifying a specific expected article within the article record thatlacks a corresponding specific identifier received within the pluralityof first RFID response signals. The second communication unit isoperative for transmitting a master signal comprising at least one of:one or more identifiers of the extra articles and one or moreidentifiers of the missing articles.

These and other aspects and features of the present invention will nowbecome apparent to those of ordinary skill in the art upon review of thefollowing description of specific embodiments of the invention inconjunction with the accompanying drawings.

BRIEF DESCRIPTIONS OF THE DRAWINGS

Embodiments of the present invention are described with reference to thefollowing figures, in which:

FIGS. 1 and 2 depict a system for wireless management of articlesaccording to a non-limiting embodiment of the present invention;

FIG. 3 depicts a non-limiting example of a memory unit within a mastertag;

FIG. 4 depicts a flow chart of steps performed by a master tag accordingto a non-limiting embodiment of the present invention;

FIG. 5 depicts a system for wireless management of articles according toan alternative non-limiting embodiment of the present invention;

FIG. 6 depicts a flow chart of steps performed by a master tag accordingto an alternative non-limiting embodiment of the present invention;

FIG. 7 depicts a system for wireless management of articles according toanother alternative non-limiting embodiment of the present invention;

FIGS. 8, 9 and 10 depict further non-limiting examples of a memory unitof a master tag;

FIGS. 11 and 12 depict flow charts of steps performed by a master tagaccording to further alternative non-limiting embodiments of the presentinvention;

FIG. 13 depicts a plurality of master tags, each coupled to a respectivepallet, according to a non-limiting example of the present invention;and

FIGS. 14 and 15 depict non-limiting examples of the memory unitscorresponding to the master tags of FIG. 13.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIG. 1 depicts a system for wireless management of articles. In someembodiments of the present invention, the system for wireless managementof articles can be implemented for inventory loaded onto a transportobject, stored in a warehouse or a storage room, displayed in a store,stored on a shelf and the like. In other embodiments of the presentinvention, the system for wireless management of articles can beimplemented for assets for an entity, such as a company, located in acommon location. Accordingly, it should be expressly understood that theterm “article” is meant to include non-exclusively an item of aninventory, an asset and the like. Therefore, it should be understoodthat the type of the articles being managed using embodiments of thesystem presented herein below should not be used as a limitation of theinvention contemplated herein.

In the specific non-limiting embodiment depicted with reference to FIG.1, the articles in question comprise a shipment of goods (not depicted),at least a portion of which is loaded onto a transport object, in thiscase a pallet 110. For the sake of simplicity, the description to bepresented herein below will use an example of the articles comprisingthe shipment of goods and the system being used for wireless inventorymanagement. However, it is expected that one of ordinary skill in theart will be able to adapt teachings presented herein to other types ofarticles that need to be managed.

In some instances, the shipment of goods may comprise items which havebeen placed in cases, one or more items to a given case. In otherinstances, the shipment of goods may comprise items loaded individuallyonto the pallet 110. In any event, the goods are tagged with inventorymanagement tags. In a non-limiting example depicted in FIG. 1, aplurality of inventory management tags 120 a, 120 b, 120 c, 120 d, areattached to different goods on the pallet 110. In some cases, each ofthe plurality of inventory management tags 120 a, 120 b, 120 c, 120 d isattached to a different case. In other cases, each of the plurality ofinventory management tags 120 a, 120 b, 120 c, 120 d is attached to adifferent item within a given case. In yet further cases, some of theplurality of inventory management tags 120 a, 120 b, 120 c, 120 d areattached to a case and yet others of the plurality of inventorymanagement tags 120 a, 120 b, 120 c, 120 d are attached to items withineach case. For the sake of simplicity, the plurality of inventorymanagement tags 120 a, 120 b, 120 c, 120 d are sometimes referred toherein below simply as tags.

Each of the plurality of inventory management tags 120 a, 120 b, 120 c,120 d is configured to store data associated with the goods to whichthey are attached, and may be implemented in software, hardware, controllogic or a combination thereof. The stored data may be stored in amemory portion (not depicted). In one non-limiting example, the storeddata comprises an identifier D1, D2, D3, D4, respectively, of the goodsto which each of the plurality of inventory management tags 120 a, 120b, 120 c, 120 d is attached. In some embodiments, each of theidentifiers D1, D2, D3, D4 comprises an inventory control number, forexample an item inventory control number, a case inventory controlnumber, depending on the nature of the goods to which each tag isattached. However, each identifier D1, D2, D3, D4 may also comprise ashipment identifier, a pallet identifier and/or, in the instance oftagged items which are placed in a case, a case identifier.

In yet further non-limiting embodiments of the present invention, eachof the plurality of inventory management tags 120 a, 120 b, 120 c, 120 dcan store additional information. This additional information can, forexample, be representative of state information of the goods that theassociated one of the plurality of inventory management tags 120 a, 120b, 120 c, 120 d is attached to. Some examples of the state informationthat can be stored within one or more of the plurality of inventorymanagement tags 120 a, 120 b, 120 c, 120 d include, but are not limitedto, production information, history information, etc. Naturally, one ormore of the plurality of inventory management tags 120 a, 120 b, 120 c,120 d can store a plethora of other information, as will become apparentto those of skill in the art.

In one non-limiting embodiment, a specific one of the identifiers D1,D2, D3, D4 that is attached to a specific product may comprise anElectronic Product Code (EPC), which includes identifiers associatedwith a manufacturer of the specific product, the specific product andthe serial number of an item of the specific product, as known to one ofskill in the art. In one non-limiting embodiment, an EPC comprises 96bits, sequentially partitioned as follows: (1) an 8 bit header; (2) a 28bit EPC manager code, for designating the organization that owns the tag(e.g. the manufacturer of the product); (3) a 24 bit object managercode, for designating the class of product as determined by the EPCmanager; and (4) a 36 bit serial number, for uniquely identifying thespecific item of the product to which the tag is attached. Hence, in ashipment of similar items, the EPC may be similar for all items, exceptfor the fourth field.

It should be expressly understood that in alternative non-limitingembodiments of the present invention, the EPC may comprise a number ofadditional fields, as well as some of the fields within the EPC may beof a size different from that specified immediately above. Within someof these non-limiting embodiments of the present invention, the EPC iscompiled according to an ISO 1800-6 c standard, a description of whichis available from http://www.hightechaid.com/standards/1800htm. However,in alternative non-limiting embodiments of the present invention, otherstandards can be used (such as, for example, other ISO 1800-x standards,etc.). In yet further non-limiting embodiments of the present invention,the specific one of the identifiers D1, D2, D3, D4 that is attached to aspecific product may be generated according to a proprietary standard.

As depicted in FIG. 1, in some embodiments of the present invention,each of the plurality of inventory management tags 120 a, 120 b, 120 c,120 d is further configured to wirelessly communicate with an inventorymanagement tag reader 140. For the sake of simplicity, the inventorymanagement tag reader 140 is sometimes referred to herein below simplyas a reader 140. In one non-limiting embodiment, each of the pluralityof inventory management tags 120 a, 120 b, 120 c, 120 d is configured towirelessly receive a read signal 142 from the reader 140 and, inresponse to receiving the read signal 142, to transmit the data storedin the respective one of the plurality of inventory management tags 120a, 120 b, 120 c, 120 d via a response signal 146 a, 146 b, 146 c, 146 d,respectively. In embodiments where the data stored comprises theidentifiers D1, D2, D3, D4, respectively, of the goods to which each ofthe plurality of inventory management tags 120 a, 120 b, 120 c, 120 d isattached, the response signal 146 a, 146 b, 146 c, 146 d comprises theidentifier D1, D2, D3, D4, respectively. Through this signal exchange,the reader 140 is able to wirelessly retrieve data from each of theplurality of inventory management tags 120 a, 120 b, 120 c, 120 d.

In some embodiments, the reader 140 may be configured to transmit aplurality of read signals 142 and receive a plurality of responsesignals 146 a, 146 b, 146 c, 146 d from each of the plurality ofinventory management tags 120 a, 120 b, 120 c 120 d. The reader 140 maybe further configured to filter out redundant response signals, in orderto filter out redundant data. In other embodiments, the filtering out ofredundant data may be performed by another entity within the system ofFIG. 1 described below.

As depicted in FIG. 1, in one non-limiting embodiment, the reader 140 isin communication with an inventory management entity 150 via acommunication network 155. Within the specific non-limiting embodimentof FIG. 1, the inventory management system 150 is embodied in astand-alone computing apparatus. However, in alternative non-limitingembodiments of the present invention, the inventory management entity150 may be embodied in a software module or a sub-system of anothersystem (for example, an inventory management system, etc.) The reader140 is configured to transmit the retrieved data, such as theidentifiers D1, D2, D3, D4 to the inventory management entity 150. Theinventory management entity 150 is configured to receive the data fromthe reader 140 and process the data for inventory management purposes,Examples of the inventory management activities include, but are notlimited to, billing, shipping, receiving, re-ordering, replenishing,restocking, maintaining, compliancy reporting, etc. The reader 140 andthe inventory management entity 150 will be described in further detailbelow, with reference to embodiments of the present invention.

In one non-limiting example, each inventory management tag 120 a, 120 b,120 c, 120 d comprises an RFID tag and the reader 140 comprises an RFIDreader. RFID tags may be passive or active devices. Passive devices arepowered through back scatter or inductively by an RF signal or amagnetic signal, respectively, transmitted from the RFID reader, whichis received by an antenna of the RFID tag. Once the RFID tag receivessufficient power, it responds by transmitting the data stored in theRFID tag memory via the antenna. Active RFID devices comprise a powersource, such as a battery, for powering a communication portion,associated circuitry and other functionality. In yet furthernon-limiting embodiments of the present invention, the RFID tag may be asemi-passive or a semi-active device as are known by one of skill in theart.

In the embodiment of FIG. 1, an inventory master tag 130 (sometimesreferred to herein below as simply a “master tag 130”) is configured forattachment to the goods which are loaded onto the pallet 110. Therefore,the inventory master tag 130 is said to be local to the plurality ofinventory management tags 120 a, 120 b, 120 c, 120 d. In someembodiments, the master tag 130 is configured for attachment to thepallet 110 itself while, in other embodiments, the master tag 130 isconfigured for attachment to an item or a case of which the shipment iscomprised or to a covering placed over and/or around the goods loaded onto the pallet 110 (the covering for securing the goods onto the pallet110). It should be understood that the means by which the master tag 130is attached should not limit the scope of the present invention.

Within the specific non-limiting embodiment of FIG. 1, the master tag130 is intended for shipment in proximity to the goods loaded onto thepallet 110 and is configured for wireless retrieval of data frominventory management tags (such as, for example, the plurality ofinventory management tags 120 a, 120 b, 120 c, 120 d). However, in analternative non-limiting embodiment of the present invention, the mastertag 130 may be configured to be attached to a particular object in aparticular location (such as, for example, a shelf/display in a store, alocation in a warehouse, etc.) or to another transport object (such as,a shipping container, a truck trailer, a train car, a case, a storagecontainer, a box, etc).

In the non-limiting example of FIG. 1, the data to be retrievedcomprises the identifiers D1, D2, D3, D4, respectively, from each of theplurality of inventory management tags 120 a, 120 b, 120 c, 120 d. Inthis case, the master tag 130 is configured to transmit one or more readsignal(s) 126 to the plurality of inventory management tags 120 a, 120b, 120 c, 120 d. The read signal(s) 126 generated by the master tag 130may be substantially similar to the read signal 142 generated by thereader 140. In response to receipt of the one or more read signal(s) 126generated by the master tag 130, each of the plurality of inventorymanagement tags 120 a, 120 b, 120 c, 120 d transmits a response signal128 a, 128 b, 128 c, 128 d, respectively. Each of the response signals128 a, 128 b, 128 c, 128 d may be similar to the response signals 146 a,146 b, 146 c, 146 d generated in response to the read signal 142generated by the reader 140, and may comprise the identifiers D1, D2,D3, D4, respectively.

In some embodiments, the master tag 130 is configured to broadcast aplurality of read signals 126 destined for the plurality of inventorymanagement tags 120 a, 120 b, 120 c, 120 d. In an alternativenon-limiting embodiment of the present invention, the master tag 130 canbe configured to send a read signal 126 specifically destined for aspecific one of the plurality of inventory management tags 120 a, 120 b,120 c, 120 d. How the master tag 130 addresses the read signal 126 tothe specific one of inventory management tags 120 a, 120 b, 120 c, 120 dis known to those of skill in the art and, as such, will not beaddressed here in any detail.

In those embodiments of the present invention, where the master tag 130transmits the read signal 126 destined to the specific one of inventorymanagement tags 120 a, 120 b, 120 c, 120 d, responsive to receiptthereof, the specific one of inventory management tags 120 a, 120 b, 120c, 120 d is configured to transmit their respective response signals 146a, 146 b, 146 c, 146 d. In those embodiments of the present invention,where the master tag 130 is configured to broadcast the plurality ofread signals 126, responsive to receipt thereof, one or more of theplurality of inventory management tags 120 a, 120 b, 120 c 120 dtransmits one or more of their respective response signals 146 a, 146 b,146 c, 146 d. The master tag 130 may be further configured to filter outredundant response signals, in order to filter out redundant data.

In non-limiting embodiments of the present invention, the master tag 130is further configured to store the retrieved data and to wirelesslytransmit it to the reader 140, via a master response signal 144. Themaster response signal 144 is generated in response to receiving a readsignal 143 generated by the reader 140. In some embodiments, the readsignal 143 is substantially similar to the read signal 142. Within theseembodiments, the read signal 143 may be further received by each of theplurality of inventory management tags 120 a, 120 b, 120 c, 120 d, whichmay, in response, generate the response signals 146 a, 146 b, 146 c, 146d, respectively. For example, in embodiments where each inventorymanagement tag 120 a, 120 b, 120 c, 120 d comprises an RFID tag, and thereader 140 comprises an RFID reader, the master response signal 144generated by the master tag 130 may comprise an RFID response signal.Hence, in response to the read signal 143, each inventory management tag120 a, 120 b, 120 c, 120 d and the master tag 130 may respond bygenerating an RFID signal for transmission to the reader 140.

In other embodiments, the read signal 143 is selectively received at themaster tag 130. In one non-limiting embodiment, the read signal 126 maybe transmitted at a first frequency, and the read signal 143 may betransmitted at a second frequency. In these embodiments, the pluralityof inventory management tags 120 a, 120 b, 120 c, 120 d may beconfigured to receive read signals at only the first frequency, whilethe master tag 130 may be configured to receive read signals at only thesecond frequency. Hence, in these embodiments, the transmission of theread signal 143 will not result in the generation of response signals146 a, 146 b, 146 c, 146 d by the plurality of inventory management tags120 a, 120 b, 120 c, 120 d.

Other embodiments for selectively receiving the read signal 143 at themaster tag 130, will be described below.

For instance, in some embodiments of the present invention as will bedescribed in detail below, the master tag 130 is further configured totransmit a blocking signal 127 to at least one of the plurality ofinventory management tags 120 a, 120 b, 120 c, 120 d. In otherembodiments, the master tag 130 is further configured to transmit ablocking signal 147 to the reader 140. The blocking signals 127 and 147are described below with reference to FIG. 6.

In embodiments where the reader 140 comprises an RFID reader and themaster response signal 144 comprises an RFID response signal, the readsignal 143 may be received at the master tag 130 when the master tag 130is in proximity of the reader 140. For the avoidance of doubt, the termRFID refers to a broad range of technologies that use RF to uniquelyidentify an article. Examples of such technologies include, but are notlimited to, ISO 1800-x based technologies, RuBee based technologies (ex.IEEE 1902.1), as well as other RFID technologies. However, in otherembodiments, the master tag 130 may be configured to receive the readsignal 143 through a wireless network (not depicted). In theseembodiments, the master tag 130 may be configured to receive the readsignal 143 when the master tag 130 is not in the proximity of the reader140. In one non-limiting embodiment, the master tag 130 and the reader140 may comprise wireless communication modules utilizing, for example,CDMA, GSM, WiMax, WiFi, satellite, Bluetooth™, Zigbee, etc. standards.Within these embodiments, the plurality of inventory management tags 120a, 120 b, 120 c, 120 d may also comprise wireless communication modules.In other embodiments, the plurality of inventory management tags 120 a,120 b, 120 c, 120 d may comprise RFID tags as described above and themaster tag 130 may be configured to communicate both with RFID tagsproximate the master tag 130 and with wireless communication modulesthrough a wireless network.

The master response signal 144 may comprise the data previouslyretrieved from the plurality of inventory management tags 120 a, 120 b,120 c, 120 d, such as the identifiers D1, D2, D3, D4 in the non-limitingexample. Hence, by communicating with the master tag 130, the reader 140may retrieve the data stored on the plurality of inventory managementtags 120 a, 120 b, 120 c, 120 d without necessarily communicating witheach of the plurality of inventory management tags 120 a, 120 b, 120 c,120 d. The master tag 130 may be implemented in software, hardware,control logic or a combination thereof.

FIG. 2 depicts a block diagram of one non-limiting embodiment of themaster tag 130 within the system depicted in FIG. 1, with likecomponents represented by like numbers. Within this embodiment, themaster tag 130 comprises a tag communication unit 132 for wirelessretrieval of data from the plurality of inventory management tags 120 a,120 b, 120 c, 120 d and a reader communication unit 134 for wirelesstransmission of data retrieved from the plurality of inventorymanagement tags 120 a, 120 b, 120 c, 120 d to the reader 140. In someembodiments, the functionality of the tag communication unit 132 and thereader communication unit 134 may be combined within a singlecommunication unit 133, as indicated by the dotted outline in FIG. 2. Inone non-limiting embodiment, the tag communication unit 132 comprises anantenna configured to exchange signals with the plurality of inventorymanagement tags 120 a, 120 b, 120 c, 120 d and the reader communicationunit 134 may also comprise an antenna configured to exchange signalswith the reader 140. In other embodiments, the tag communication unit132 and the reader communication unit 134 could share a common antenna.

As depicted in FIG. 2, the master tag 130 further comprises a processingunit 136 and a memory unit 138 coupled to the tag communication unit 132and the reader communication unit 134. The processing unit 136 isconfigured to perform various functions to be described herein below andmay be implemented in software, hardware, control logic or a combinationthereof. The memory unit 138 is configured to store inventory data,including data retrieved from the plurality of inventory management tags120 a, 120 b, 120 c, 120 d. Among other functions, the processing unit136 is configured to process data received at the tag communication unit132 and/or the reader communication unit 132 and/or the data stored atthe memory unit 138.

FIG. 3 depicts a non-limiting example of the memory unit 138. Withinthis non-limiting example, the memory unit 138 comprises a record 310,for storing an identifier of the master tag 130, for example anidentification number. In one non-limiting example, the identifier ofthe master tag 130 may comprise an EPC, though it should be understoodthat any appropriate identifier format could be utilized. In onenon-limiting example, the identifier of the master tag 130 may be storedat the memory 138 at the time of manufacture. In other non-limitingexamples, the identifier of the master tag 130 may be stored at thememory 138 during a provisioning process which may occur before or afterthe master tag 130 is attached to the pallet 110. As depicted in FIG. 3,the memory unit 138 further comprises a tag data record 320 (sometimesreferred herein below as simply a “record 320”), which contains aplurality of fields for storing data received by the tag communicationunit 132. In general, the number of fields is not particularly limited,except by the size of the memory. Although the record 320 is shown withsix fields, more or fewer fields are within the scope of the invention.

Returning to the description of FIG. 2, components of the master tag 130(for example, at least some of the reader communication unit 134, thetag communication unit 132, the processing unit 136 and the memory unit138) may be powered by a power source 139. As will occur to one of skillin the art, the power source 139 may comprise an battery, or aconnection to another power source associated with the pallet 110.

A method for wireless inventory management according to a non-limitingembodiment of the present invention will now be described with referenceto FIG. 4. In order to assist in the explanation of the method, it willbe assumed that the method of FIG. 4 is operated using embodiments ofthe master tag 130 depicted in FIG. 2. It should be understood that thesteps in the method of FIG. 4 need not be performed in the sequenceshown. Further, it is to be understood that the master tag 130 of FIG. 2and/or the method of FIG. 4 can be varied, and need not work asdiscussed herein in conjunction with each other, and that suchvariations are within the scope of the present invention.

At step 510, the master tag 130 transmits a request for inventorymanagement tag data. Within the embodiment depicted in FIG. 2, therequest for inventory management tag data comprises the read signal 126,which is transmitted to the plurality of inventory management tags 120a, 120 b, 120 c, 120 d by the tag communication unit 132. Thetransmission of the read signal 126 by the tag communication unit 132may be in response to a trigger received from the processing unit 136.In some non-limiting embodiments, the tag communication unit 132transmits a single read signal 126; however, in other non-limitingembodiments, the tag communication unit 132 may transmit a plurality ofread signals 126. In some embodiments of the present invention, the tagcommunication unit 132 may transmit the plurality of read signals 126 ina periodic manner. Within these embodiments, the processing unit 136 mayfurther comprise or be coupled to a timing device (not depicted) and theprocessing unit 136 may be configured to transmit a trigger to the tagcommunication unit 132 at periodic intervals. However, otherarrangements as to how the tag communication unit 132 may transmit theplurality of read signals 126 are possible.

At step 520, in response to transmitting the request for inventorymanagement tag data, the master tag 130 receives inventory managementtag data. Continuing with the example depicted in FIG. 2, the inventorymanagement tag data may be received at the tag communication unit 132 asresponse signals 128 a, 128 b, 128 c, 128 d, from the respective ones ofthe plurality of inventory management tags 120 a, 120 b, 120 c, 120 d.In some embodiments, the tag communication unit 132 is configured toreceive a plurality of response signals concurrently.

In other non-limiting embodiments, the tag communication unit 132 may beconfigured to receive and process one response signal at a time. Inthese embodiments, the tag communication unit 132 may be configured toignore successive response signals until a current response signal hasbeen received and processed. In other words, the tag communication unit132 may be operable to process response signals in a First In First Out(FIFO) basis. In other embodiments, First Expire First Out (FEFO) orother algorithms can be used.

In embodiments where the read signal 126 is transmitted in a periodicmanner, each of the plurality of inventory management tags 120 a, 120 b,120 c, 120 d, may transmit a response signal 128 a, 128 b, 128 c, 128 d,respectively, in response to each read signal 126 received. Within theseembodiments, the processing unit 136 may be configured to filter outredundant inventory management tag data received. In one non-limitingembodiment, the processing unit 136 may be configured to filter outredundant inventory management tag data received by comparing theinventory management tag data received with the inventory management tagdata previously received. This comparison may occur after the inventorymanagement tag data received is stored in the memory unit 138, describedin relation to step 530, or prior to storing the inventory managementtag data received in the memory unit 138.

In an alternative non-limiting embodiment of the present invention, themaster tag 130 may first broadcast a plurality of read signals 126 tothe plurality of inventory management tags 120 a, 120 b, 120 c, 120 d.Alternatively, the master tag 130 may keep broadcasting a plurality ofread signals 126 to the plurality of inventory management tags 120 a,120 b, 120 c, 120 d in a periodic manner for a pre-determined period oftime (such as, for example, 30 seconds, 1 minutes, 5 minutes, 30minutes, 1 hour, etc.). Thereafter, the master tag 130 may transmit aread signal 126 destined for a particular one of the plurality ofinventory management tags 120 a, 120 b, 120 c, 120 d. The particular oneof the plurality of inventory management tags 120 a, 120 b, 120 c, 120 dincludes those of the plurality of inventory management tags 120 a, 120b, 120 c, 120 d that has not transmitted its respective response signal128 a, 128 b, 128 c, 128 d.

In some embodiments, all of the response signals 128 a, 128 b, 128 c,128 d may be received, representing a full accounting of the inventoryof goods present on the pallet 110. However, in other embodiments, someof the response signals 128 a, 128 b, 128 c, 128 d may not be received,representing only a partial accounting of the inventory of goods presenton the pallet 110.

In some embodiments of the present invention, as part of step 530, oncethe master tag 130 has received a specific response signal (i.e. one ofthe response signals 128 a, 128 b, 128 c, 128 d) from a specific one ofthe plurality of inventory management tags 120 a, 120 b, 120 c, 120 d,the master tag 130 may be configured to temporarily disable the specificone of the of the plurality of inventory management tags 120 a, 120 b,120 c, 120 d. This can be done, for example, by transmitting a controlsignal for causing the specific one the plurality of inventorymanagement tags 120 a, 120 b, 120 c, 120 d to enter a “SLEEP” mode. Anyother suitable approach for causing the specific one of the plurality ofinventory management tags 120 a, 120 b, 120 c, 120 d to be temporarilydisabled can be used. In an alternative non-limiting embodiment of thepresent embodiment, the specific one of the plurality of inventorymanagement tags 120 a, 120 b, 120 c, 120 d can automatically enter thesleep mode upon transmission of the specific response signal. Yet infurther non-limiting embodiments, the specific one of the plurality ofinventory management tags 120 a, 120 b, 120 c, 120 d can enter the sleepmode upon elapse of a pre-determined time interval (ex. 30 seconds, 1minute, 5 minutes, 10 minutes, 1 hour, etc.) from the transmission ofthe specific response signal.

At step 530, the memory unit 138 stores the received inventorymanagement tag data. In some embodiments, the tag communication unit 132is configured to pass the inventory management tag data receiveddirectly to the memory unit 138 for storage. In other embodiments, thetag communication unit 132 is configured to pass the inventorymanagement tag data received to the processing unit 136, which thenpasses the data to the memory unit 138 for storage. Within theseembodiments, the processing unit 136 may be configured to process theinventory management tag data received for storage. Within onenon-limiting example, the processing unit 136 compresses the inventorymanagement tag data received to reduce the amount of space needed tostore the inventory management tag data at the memory unit 138. In otherembodiments, the processing unit 136 is configured to organize theinventory management tag data prior to storage at the memory unit 138.In one non-limiting example, the processing unit 136 may organize thetag data received in numerical and/or alphabetical order.

In some embodiments, the inventory management tag data received isstored in the record 320 of the memory unit 138, as depicted in FIG. 3.Although the record 320 is depicted with the inventory management tagdata in numerical order of the identifiers D1, D2, D3, D4 of theplurality of inventory management tags 120 a, 120 b, 120 c, 120 d,respectively, the order in which the inventory management tag data isstored is not particularly limited. For example, the inventorymanagement tag data may also be stored in the order the inventorymanagement tag data was received, or in a random order.

Within other embodiments, the processing unit 136 is configured toformat the identifiers D1, D2, D3, D4 into a single data set for latertransmission to the reader 140, the single data set also stored at thememory unit 138. In some embodiments, the single data set may be storedin the record 320; however, in other embodiments, the single data setmay be stored in another record (not depicted) of the memory unit 138.Within embodiments where the single data set is stored at the memoryunit 138, the individual identifiers D1, D2, D3, D4 may not be stored,as the storing of the individual identifiers D1, D2, D3, D4 may beredundant.

At step 540, the processing unit 136 is configured to determine if aninventory management tag data read request has been received. In onenon-limiting embodiment, the inventory management tag data read requestmay comprise the read signal 143 generated by the reader 140 beingreceived at the reader communication unit 134. In embodiments where theread signal 143 comprises an RFID read signal, the RFID read signal maybe received when the master tag 130 is in proximity of the reader 140.In other embodiments, where the master tag 130 and the reader 140comprise wireless communication modules, the read signal 143 may bereceived through a wireless communication network (not depicted), asdescribed above.

If an inventory management tag data request has been received, then atstep 550, the master tag 130 is configured to transmit the inventorymanagement tag data to the reader 140. In some embodiments, the readercommunication unit 134 is configured to transmit the master responsesignal 144; the master response signal 144 comprising at least a portionof the tag data stored at the record 320. Within other non-limitingembodiments, the master response signal 144 may further comprise themaster tag identifier stored at the record 310 and/or processed versionsof the tag data stored at the record 320 (i.e. the aforementioned singledata set). The inventory management tag data may be transmitted in theorder stored at the memory 138, or it may be transmitted in anotherorder. In some embodiments, the master response signal 144 may comprisea single transmission, the single transmission comprising a single dataset comprising all of the tag data stored at the memory unit 138. Forexample, the master response signal 144 may comprise the identifiers D1,D2, D3, D4 transmitted in a single transmission. Within theseembodiments, the processing unit 136 may be configured to retrieve theidentifiers D1, D2, D3, D4, format the identifiers D1, D2, D3, D4 into aconsolidated data set for transmission to the reader 140, and pass theconsolidated data set to the reader communication unit 134 fortransmission to the reader 140 via the master response signal 144.Within these embodiments, the receipt of the consolidated data set atthe reader communication unit 134 may trigger the transmission of themaster response signal 144.

In embodiments where the single data set is processed as the identifiersD1, D2, D3, D4 are received, and the single data set is saved at thememory unit 138 as described above, the processing unit 136 may beconfigured to retrieve the single data set, format the single data setfor transmission to the reader 140, and pass the formatted single dataset to the reader communication unit 134, for transmission to the reader140 via the master response signal 144.

In some embodiments, the inventory management tag data may not be storedin a format which is suitable for handling by the reader 140. In theseembodiments, the processing unit 136 may be configured to process theinventory management tag data into a format that is suitable forhandling by the reader 140, prior to transmission of the master responsesignal 144. For example, in embodiments where the inventory managementtag data is compressed or encrypted, the processing unit 136 may beconfigured to de-compress or decrypt the inventory management tag data.

In further non-limiting embodiments, the master response signal 144 maycomprise a plurality of transmissions, each of the plurality oftransmissions comprising at least one inventory management tag datum.Within these embodiments, the processing unit 136 may be configured toretrieve the identifiers D1, D2, D3, D4, format each of the identifiersD1, D2, D3, D4 into a format suitable for transmission to the reader140, and pass the formatted identifiers to the reader communication unit134 for transmission to the reader 140 via the master response signal144. Within these embodiments the receipt of one or more formattedidentifier(s) at the reader communication unit 134 may trigger thetransmission of a master response signal 144.

In some embodiments, once the inventory management tag data has beentransmitted, the master tag 130 may continue to request inventorymanagement tag data at step 510, in preparation for further readrequests. In other embodiments, the master tag 130 may not continue torequest inventory management tag data, but may respond to further readrequests at step 540. In embodiments where the master tag 130 comprisesa timing device, the master tag 130 may continue to request inventorymanagement tag only for a given time period. In other embodiments, themaster tag 130 may not continue to request inventory management tag dataif all expected inventory management tag data is already stored at therecord 320 as will be described in greater detail herein below. In yetother embodiments, the master tag 130 may transmit only a defined numberof inventory management tag data read requests.

In further non-limiting embodiments, the master tag 130 may beconfigured to undergo an end procedure at step 560. In some embodiments,the end procedure may include clearing the memory unit 138 of storeddata. In other embodiments, the end procedure may include shutting downpower or entering a sleep state, in order to preserve the power source139. In some embodiments, the master tag 130 may further comprise aswitch (not depicted) to turn power back on, or to exit the sleep state.Within other embodiments, at least one of the reader communication unit134 and the tag communication unit 132 may be configured to receive a“WAKE” command from a provisioning entity to turn the master tag 130back on. In some embodiments the provisioning entity may comprise thereader 140.

Reference is now made to FIG. 5, which depicts an alternativenon-limiting embodiment of a system for wireless inventory management ofa shipment of goods. The system depicted in FIG. 5 is substantiallysimilar to the system depicted in FIG. 1, with like components depictedwith like numbers; however, a master tag 130′ of FIG. 5 which is similarto the master tag 130 further comprises a blocker unit 610, coupled tothe processing unit 136, for blocking communication between theplurality of inventory management tags 120 a, 120 b, 120 c, 120 d, andthe reader 140. In some embodiments, the functionality of the blockerunit 610 may be combined with the tag communication unit 132, the readercommunication unit 134 or a combined communication unit 133′ (similar tothe combined communication unit 133 but further comprising the blockerunit 610), as indicated by the dotted outline in FIG. 5. The blockerunit 610 comprises an antenna which may be shared with the tagcommunication unit 132 and/or the reader communication unit 134. In someembodiments, the antenna is configured to exchange signals with theplurality of inventory management tags 120 a, 120 b, 120 c, 120 d,while, in other embodiments, the antenna is configured to exchangesignals with the reader 140.

Generally speaking, the blocker unit 610 can be configured to block aspecific one of the plurality of inventory management tags 120 a, 120 b,120 c, 120 d. In an alternative non-limiting embodiment, the blockerunit 610 can be configured to block a set of inventory management tags(such as, a group comprising some or all of the plurality of inventorymanagement tags 120 a, 120 b, 120 c, 120 d). Alternatively, the blockerunit 610 can be configured to block all of the plurality of inventorymanagement tags 120 a, 120 b, 120 c, 120 d located within apre-determined distance therefrom.

Embodiments which demonstrate the functionality of the blocker unit 610will now be described with reference to FIG. 6, which depicts a methodfor wireless inventory management according to an alternativenon-limiting embodiment. In order to assist in the explanation of themethod, it will be assumed that the method of FIG. 6 is operated usingthe embodiment of the master tag 130′ depicted in FIG. 5.

The method depicted in FIG. 6 is substantially similar to the methoddepicted in FIG. 4, with like steps represented by like numbers.However, the method depicted in FIG. 6 further comprises a step 735 ofblocking the inventory management tags from communicating with thereader 140, once the inventory management tag data has been received atstep 520 and/or stored in the memory unit 138 at step 530. The methoddepicted in FIG. 6 further comprises a step 755 to unblock the inventorymanagement tags from communicating with the reader 140, once the mastertag 130′ has transmitted the inventory management tag data to the reader140.

Within non-limiting embodiments where the blocker unit 610 is configuredto communicate with the plurality of inventory management tags 120 a,120 b, 120 c, 120 d, the blocker unit 610 may be configured to transmita blocking signal 127 at step 735 to one or more of the plurality ofinventory management tags 120 a, 120 b, 120 c, 120 d. Specifically,blocker unit 610 may send a blocking signal 127 to the plurality ofinventory management tags 120 a, 120 b, 120 c, 120 d whose data has beenreceived at the master tag 130. Within this non-limiting embodiment, theblocking signal 127 may comprise a blocking command instructing at leastone of the plurality of inventory management tags 120 a, 120 b, 120 c,120 d not to respond to further requests for inventory management tagdata. In some embodiments, the blocking command may comprise a “SLEEP”or a “DISABLE” command. Within these embodiments, the plurality ofinventory management tags 120 a, 120 b, 120 c, 120 d which receive andprocess the blocking command may not respond to further requests forinventory management tag data from either the reader 140, or from themaster tag 130′ itself.

In embodiments where the plurality of inventory management tags 120 a,120 b, 120 c, 120 d comprise RFID tags, the blocking signal 127 maycomprise a plurality of signals, each signal for engaging a specificRFID tag in one of a plurality of read sessions. RFID tags typically maybe engaged in multiple read sessions, to a maximum number of readsessions. Hence, in this embodiment, the blocking signal 127 maycomprise a plurality of signals for engaging each of the RFID tags intothe maximum number of read sessions. In a non-limiting example, if themaximum number of read sessions that an RFID tag may be engaged in isthree concurrent read sessions at any given point of time, then theblocking signal 127 may comprise three signals intended for a specificRFID tag, each signal for engaging the RFID tag in a read session. Inthis non-limiting scenario, the RFID tag is unable to respond to furtherrequests for tag data from either the reader 140 or the master tag 130′itself.

Within non-limiting embodiments where the blocking signal 127 istransmitted to one or more of the plurality of inventory management tags120 a, 120 b, 120 c, 120 d, the plurality of inventory management tags120 a, 120 b, 120 c, 120 d are configured to be addressable by themaster tag 130′. Within these embodiments, the blocking signal 127 maycomprise an identifier(s) of the inventory management tag(s) 120 a, 120b, 120 c, 120 d that are to be blocked In one non-limiting embodiment,the identifier(s) may comprise one or more of the identifiers D1, D2,D3, D4 stored at the plurality of inventory management tags 120 a, 120b, 120 c, 120 d. Within these embodiments, the plurality of inventorymanagement tags 120 a, 120 b, 120 c, 120 d may be configured to acceptthe blocking command instructing it not to respond to further requestsfor inventory management tag data, only if the blocking signal 127comprises the corresponding identifier D1, D2, D3, D4.

In non-limiting embodiments in which the plurality of inventorymanagement tags 120 a, 120 b, 120 c, 120 d are configured to receive theblocking command, once the blocking command is received, the pluralityof inventory management tags 120 a, 120 b, 120 c, 120 d are furtherconfigured to process the blocking command and, in response, to notrespond to further requests for inventory management tag data. In anon-limiting example, once the blocking command has been processed byone of the plurality of inventory management tags 120 a, 120 b, 120 c120 d, that tag may not transmit the response signal 128 a, 128 b, 128c, 128 d, respectively, if the read request 143 or the read request 126is received. In this manner, when the reader 140 transmits an inventorymanagement tag data read request to the master tag 130′ at step 540 ofFIG. 4, for example, a given one of the plurality of inventorymanagement tags 120 a, 120 b, 120 c, 120 d which has previouslyprocessed the blocking signal 127 will not respond to any furtherinventory management tag data read request (such as, for example, afurther read request 143). Hence, in some embodiments, the read request143 can result only in the response 144 from the master tag 130′. Thisprevents the reader 140 from receiving redundant data and furthermitigates the reader 140 from becoming overly busy processing largenumbers of response signals at one time. In addition, further readrequests from the master tag 130′, for example the read signal 126, mayalso be ignored. This can relieve the master tag 130′ from filteringredundant data.

In embodiments where at least one of the plurality of inventorymanagement tags 120 a, 120 b, 120 c, 120 d has not been blocked and,therefore, is considered to be an “unblocked inventory management tag”,the read request 143 may also result in a response 128 a, 128 b, 128 c,128 d, respectively, from the at least one unblocked inventorymanagement tag.

In some non-limiting embodiments, some of the plurality of inventorymanagement tags 120 a, 120 b, 120 c, 120 d may not have been blocked asthe master tag 130′ may not have been able to retrieve the data fromthese inventory management tags. Within these embodiments, the readrequest 143 from the reader 140 may result in a response signal 128 a,128 b, 128 c, 128 d from the unblocked inventory management tags. Inthis case, the reader 140 may receive the master response signal 144 aswell as one or more of the response signals 128 a, 128 b, 128 b, 128 d,which overall may provide a more complete accounting of the inventory ofthe goods on the pallet 110.

In other non-limiting embodiments, some of the plurality of inventorymanagement tags 120 a, 120 b, 120 c, 120 d may not have been blocked asthe blocking signal 127 may not have been received or properly processedat these inventory management tags. In some embodiments, this may be dueto the configuration of the goods present on the pallet 110. Withinthese embodiments, the read request 143 from the reader 140 may resultin a response 128 a, 128 b, 128 c, 128 d from unblocked inventorymanagement tags. The response 128 a, 128 b, 128 c, 128 d may includedata which is also present in the master response signal 144. In theseembodiments, the reader 140 may be further configured to filterredundant data or pass the redundant data to the inventory managemententity 150.

As depicted in FIG. 6 at step 755, in some non-limiting embodiments, theblocking unit 610 may further be configured to unblock any of theplurality of inventory management tags 120 a, 120 b, 120 c, 120 d thatwere blocked at step 735, This unblocking step in non-limitingembodiments occurs once the tag data has been transmitted from themaster tag 130′ to the reader 140 at step 550. In embodiments where ablocking command has been transmitted to one or more of the plurality ofinventory management tags 120 a, 120 b, 120 c, 120 d at step 735, theblocking unit 610 may be configured to transmit an unblocking command tothe plurality of inventory management tags 120 a, 120 b, 120 c, 120 d atstep 755; the unblocking command for instructing the one or more of theplurality of inventory management tags 120 a, 120 b, 120 c or 120 d thatwere previously blocked to respond to further requests for tag data. Insome non-limiting embodiments, the unblocking command may comprise a“WAKE” or an “ENABLE” command. In other embodiments, where the blockingsignal 127 of step 735 comprises a plurality of signals for engaging oneor more of the plurality of inventory management tags 120 a, 120 b, 120c, 120 d in the maximum number of read sessions possible, the blockingunit 610 may be configured to terminate one or more of the read sessionswith the blocked tags (for example, in some cases, ceasing to transmitthe blocking signal 127). In this case, the plurality of inventorymanagement tags 120 a, 120 b, 120 c, 120 d may respond to furtherrequests for tag data.

In some non-limiting embodiments, the unblocking command (which may bewithin an unblocking signal similar to the blocking signal 127), may betransmitted to all of the plurality of inventory management tags 120 a,120 b, 120 c, 120 d, instructing/enabling them to respond to furtherrequests for inventory management tag data. In other embodiments, aplurality of unblocking signals may be transmitted, each comprising anunblocking command intended for a specific inventory management tag 120a, 120 b, 120 c, 120 d. In these embodiments, the signals may furthercomprise an identifier of the inventory management tag 120 a, 120 b, 120c, 120 d, as described above.

In these non-limiting embodiments, the plurality of inventory managementtags 120 a, 120 b, 120 c, 120 d are configured to receive the unblockingsignal(s), and to extract the unblocking command. The plurality ofinventory management tags 120 a, 120 b, 120 c, 120 d are furtherconfigured to process the unblocking command and, in response, respondto further requests for inventory management tag data. Once again, itshould be understood that in some non-limiting embodiments, theunblocking signal could be the same as the blocking signal 127 butterminating the sessions initiated to utilize the maximum number ofsessions available to the tag. Hence, in this case, the unblockingsignal enables the tag to initiate further data read sessions with otherreaders or the master tag 130′.

In some non-limiting embodiments, the blocking unit 610 may beconfigured to communicate with the reader 140. Within these embodiments,at step 735, the blocking unit 610 may be configured to transmit ablocking signal 147 to the reader 140, in order to block the reader 140from communicating with the one or more of the plurality of inventorymanagement tags 120 a, 120 b, 120 c, 120 d, whose data has been receivedat the master pallet tag 130′. In some non-limiting embodiments, theblocking signal 147 can comprise a signal that indicates which responsesignals to reject and/or not process.

In non-limiting embodiments where the plurality of inventory managementtags 120 a, 120 b, 120 c, 120 d comprise RFID tags and the reader 140comprises an RFID reader, the RFID reader may be blocked fromcommunicating with the RFID tags by transmitting the blocking signal 147to the reader 140 if the blocking signal 147 simulates at least aportion of the response signal 128 a, 128 b, 128 c, 128 d.

In general, RFID readers may communicate with one RFID tag at a time. Asdescribed above, if the RFID reader receives more than one RFIDresponse, the reader may detect a collision of signals and execute asingulation algorithm, which allows the reader to communicate withconflicting RFID tags, one at a time. Methods of blocking RFID tags frombeing read by interfering with this singulation algorithm are describedin U.S. patent application Ser. No. 10/673,540 which is incorporatedherein by reference. Generally speaking, blocker algorithms block RFIDtags whose identifiers share a common prefix from communicating with theRFID reader. For example, in the embodiment where the RFID tagidentifier is an EPC, the blocker unit 610 may transmit a blockingsignal 147 for blocking RFID tags having a particular range of headers,a particular range of EPC manager codes, a particular range of objectmanager codes, or a particular range of serial numbers.

Therefore, in non-limiting embodiments where the plurality of inventorymanagement tags 120 a, 120 b, 120 c, 120 d, whose data has beenretrieved by the master tag 130′, share a common prefix, the blockerunit 610 may transmit a blocking signal 147 which blocks the reader 140from communicating with those inventory management tags 120 a, 120 b,120 c, 120 d. In some embodiments, the blocking signal 147 may alsoblock the master tag 130′ itself from communicating with those inventorymanagement tags 120 a, 120 b, 120 c, 120 d.

In these embodiments, at step 755, the blocker unit 610 may beconfigures to cease to transmit the blocking signal 147 which interfereswith the singulation algorithm at the reader 140. In other non-limitingembodiments, the blocking unit 610 could transmit an unblock signal tothe reader 140 at step 755.

In another non-limiting embodiment, the blocker unit 610 may beconfigured to communicate with both the reader 140 and the plurality ofinventory management tags 120 a, 120 b, 120 c, 120 d. Within thisembodiment, the blocker unit 610 may transmit a code to each of theplurality of inventory management tags 120 a, 120 b, 120 c, 120 d as itis read, to ensure that those inventory management tags 120 a, 120 b,120 c, 120 d that have been read share a common prefix. In thisembodiment, the master tag 130′ is further configured to transmit thecode to individual inventory management tags 120 a, 120 b, 120 c, 120 d,similar to the method of addressing individual inventory management tags120 a, 120 b, 120 c, 120 d as described above. In embodiments where theplurality of inventory management tags 120 a, 120 b, 120 c, 120 dcomprise RFID tags and the identifiers D1, D2, D3, D4 comprise an EPC,the master tag 130′ may transmit the code to RFID tags which have beenread, for causing a change in a leading bit or bits of the serialnumber. In one non-limiting embodiment, this code may be transmitted viathe blocking signal 127. In this embodiment, the master tag identifier,stored in the memory unit 138, may also comprise an EPC, which shares acommon leading bit or bits of the serial number with unread RFID tags.In a non-limiting example, the leading bit on all unread, and henceunblocked, RFID tags may be “0”. In addition, the leading bit in themaster tag identifier may also be “0”. As the RFID tags are read, theblocker unit 610 may transmit a tag specific key to each RFID tag,causing the leading bit to flip to “1”. In the presence of the reader140, the blocker unit 610 may then block the reader 140 from reading allRFID tags that are associated with a serial number with the leading bitof “1”.

In this case, the reader 140 will be able to retrieve the data from themaster tag 130′, as well as the data from any of the unblocked RFIDtags.

In these embodiments, at step 755, the blocker unit 610 may ceasetransmitting the blocking signal 147 which interferes with thesingulation algorithm at the reader 140. As well, the blocker unit 610may further transmit a tag specific key to each RFID tag which has beenread, causing the leading bit to flip back to its original value, forexample from a “1” to a “0”.

Although described above with a prefix and with the specific “0” and “1”bits identifying read and unread tags, it should be understood that manyother options are possible. For instance, other bits could be modifiedwithin or outside of the identifiers (such as the EPC) to indicate thata tag has been read or unread. Further, in other non-limitingembodiments, a separate flag bit could be maintained on the tags tomanage the indication of whether they have been read or not.

FIG. 7 depicts another non-limiting embodiment of the present invention,in which a blocker tag 810 is further attached to the pallet 110, in amanner similar to that described above with reference to the master tag130. FIG. 7 is substantially similar to FIG. 2, with like componentsrepresented by like numbers. The blocker tag 810 may incorporate all ofthe functionality described with respect to the blocker unit 610described above. In some embodiments, the blocker tag 810 may beconfigured to prevent tags with a given prefix from being read. In theseembodiments, the blocker tag 810 may comprise a blocker unit 710 similarto blocker unit 610 of FIG. 5 and a memory unit 820 for storing thegiven prefix and associated blocking data.

In some non-limiting embodiments, the master tag 130 of FIG. 2 may beconfigured to transmit a tag specific key which sets the prefix of allread tags to the given prefix, similar to the example described above,via the blocking signal 127.

In other embodiments, this functionality may reside at the blocker tag810, with the master tag 130 being further configured to communicate theidentifiers D1, D2, D3, D4 of inventory management tags 120 a, 120 b,120 c, 120 d whose data has been retrieved by the master tag 130 to theblocker tag 810. Within these non-limiting embodiments, the blocker tag810 comprises a master tag communication unit 825 for communicating withthe master tag 130. The master tag communication unit 825 can be similarto the tag communication unit 132 and/or the reader communication unit134 described above, and is configured to receive a signal 822 whichcomprises the identifiers D1, D2, D3, D4, of the plurality of inventorymanagement tags 120 a, 120 b, 120 c, 120 d, which have been retrieved bythe master tag 130. The tag communication unit 132 or the readercommunication unit 134 at the master tag 130 may be configured totransmit the identifiers of inventory management tags 120 a, 120 b, 120c, 120 d which are stored in the memory unit 138 via the signal 822. Inthese non-limiting embodiments, the blocker unit 710 is configured totransmit a tag specific key which sets the prefix of all read tags tothe given prefix, similar to the example described above. The tagspecific key may be transmitted via a blocking signal 827 transmitted bythe blocker unit 710. In these non-limiting embodiments, the memory unit820 is further configured for storing identifiers D1, D2, D3, D4 thatare received from the master tag 130. As depicted in FIG. 7, the blockertag 810 further comprises a processing unit 830 similar to theprocessing unit 136 described above, for processing data received fromthe master tag 130, and for managing data stored at the memory unit 820.

In embodiments where the blocker tag 810 is configured to block specificranges of identifiers D1, D2, D3, D4, the processing unit 830 may beconfigured to identify prefixes that the identifiers D1, D2, D3, D4 havein common, for example at the serial number level. The processing unit830 may then be further configured to trigger the blocker unit 710 toblock the reader 140 from reading those ranges of identifiers bytransmitting the blocking signal 147.

Similar to the description for FIG. 6, although described above with aprefix identifying read and unread tags, it should be understood thatmany other options are possible. For instance, other bits could bemodified within or outside of the identifiers (such as the EPC) toindicate that a tag has been read or unread. Further, in othernon-limiting embodiments, a separate flag bit could be maintained on thetags to manage the indication of whether they have been read or not,this flag being changed by the master tag 130 or the blocker tag 810.

Similar to the combined communication unit 133 of FIG. 2 and thecombined communication unit 133′ of FIG. 5, the blocker unit 710 and themaster tag communication unit 825 may be combined into combinedcommunication unit 860, as indicated by the dotted outline in FIG. 7.Similar to the power source 139 described above with reference to FIG.2, the blocker tag 810 may have a power source 850.

FIG. 8 depicts another non-limiting example of the memory unit 138depicted in FIG. 3, with like components depicted with like numbers.Within FIG. 8, the memory unit 138 further comprises an inventory record910, which contains a plurality of fields for storing identifiers ofgoods loaded onto the pallet 110. In general, the number of fields isnot particularly limited, except by the size of the memory. Although therecord 910 is shown with six fields, more or fewer fields are within thescope of the invention. In one non-limiting embodiment, the inventoryrecord 910 comprises at least a portion of an Advance Shipment Notice(ASN), which may identify purchase order numbers, stock keeping unit(SKU) numbers, similar to the serial number of an item of a product, lotnumbers, quantity, pallet or container number, and/or carton number. Inone non-limiting embodiment, the inventory record 910 comprises a listof identifiers D1, D2, D3, D4 associated with the plurality of inventorymanagement tags 120 a, 120 b, 120 c, 120 d, these identifiers D1, D2,D3, D4 representing the goods that are present on the pallet 110 of FIG.2 or FIG. 7. The inventory record 910 may be populated in a priorprovisioning step, for example at the time of loading the pallet 110with the goods.

Within the example depicted in FIG. 8, the inventory record 910comprises identifiers D1, D2, D3, D4, and the tag data record 320comprises identifiers D1, D2, D3, D4. Hence, within this example, all ofthe plurality of inventory management tags 120 a, 120 b, 120 c, 120 dattached to the goods that were loaded onto the pallet 110 and recordedwithin the inventory record 910 were read by the master tag 130.

FIG. 9 depicts another non-limiting example of the memory unit 138depicted in FIG. 8, with like components depicted with like numbers.Within this non-limiting example, the inventory record 910 comprisesidentifiers D1, D2, D3, D4 and the tag data record 320 comprisesidentifiers D1, D2, D3, D4, D5. Hence, within this example, the tag datarecord 320 indicates that an inventory management tag comprising theidentifier D5 was read by the master tag 130. However, as the identifierD5 is not present in the inventory record 910, there is a discrepancy inthe accounting of the inventory. In some embodiments, this may indicatethat a mistake was made during the loading process and that an extraitem was loaded onto the pallet 110. In other embodiments, this mayindicate that a mistake was made in provisioning the inventory record910. In yet other embodiments, this may indicate that the item havingthe identifier D5 may be in the proximity of the master tag 130, but maynot actually be loaded onto the pallet 110. This last situation mayoccur in situations where a shipment of goods comprises a plurality ofpallets, each potentially having a separate master tag similar to themaster tag 130 attached to each pallet (for example see FIG. 13).

FIG. 10 depicts yet another non-limiting example of the memory unit 138depicted in FIG. 8, with like components depicted with like numbers.Within this embodiment, the inventory record 910 comprises identifiersD1, D2, D3, D4, and the tag data record 320 comprises identifiers D1,D2, D3. Hence, within this example, the tag data record 320 indicatesthat the inventory management tag comprising the identifier D4 was notread by the master tag 130. However, as the identifier D4 is present inthe inventory record 910, there is a discrepancy in the accounting ofthe inventory. This may indicate that a mistake was made during theloading process and that either an item was not loaded onto the pallet110, or a mistake was made in provisioning the inventory record 910.However, the tag data record 320 and the inventory record 910 may alsoindicate that if the item with the identifier D4 is present on thepallet 110, the inventory management tag which is attached to the itemmay not be readable by the master tag 130.

One embodiment of the present invention which includes a master tag 130that comprises the inventory record 910 will now be described withreference to FIG. 11, which depicts a method for wireless inventorymanagement. In order to assist in the explanation of the method, it willbe assumed that the method of FIG. 11 is operated using the systemdepicted in FIG. 5. The method depicted in FIG. 11 is substantiallysimilar to the method depicted in FIG. 6, with like steps represented bylike numbers. However, the method depicted in FIG. 11 further comprisesa step 1235 in which the master tag 130 determines if the inventorymanagement tag data received at step 520 is present in the inventoryrecord 910. In a non-limiting embodiment, the step 1235 is executablewithin the processing unit 136. In alternative embodiments, the step1235 could be performed prior to the storing of the tag data at step530.

As depicted in FIG. 11, if the processing unit 136 determines that theinventory tag data received is present in the inventory record 910, themaster tag 130 proceeds to block the one or more of the plurality ofinventory management tags 120 a, 120 b, 120 c, 120 d that were read fromcommunicating with the reader 140 and, in some embodiments, fromresponding to further requests for data from the master tag 130, in themanner described above. If all the inventory management tag dataretrieved is present in the inventory record 910, for example in theembodiment depicted in FIG. 8, than all of the plurality of inventorymanagement tags 120 a, 120 b, 120 c, 120 d are blocked fromcommunicating with the reader 140 and, in some embodiments, with the tagcommunication unit 132.

If it is determined at step 1235 that the inventory management tag datareceived at step 520 is not present in the inventory record 910, theinventory management tag(s) that comprise identifiers which were readare not blocked from communicating with the reader 140, the master tag130 or other master tags (not depicted) that may be sufficiently closeto read the inventory management tag(s). In this case, the inventorymanagement tag(s) read may correspond to goods that are located onanother pallet. Therefore, in many scenarios, it would not be desirableto block the inventory management tag. In these embodiments, furtherrequests for inventory management tag data, at step 510, could result infurther receipt of inventory management data from the unblockedinventory management tags.

In some circumstances, an unblocked inventory management tag may stopresponding to the further requests for inventory management tag data.This situation may occur, for example, if the item to which theunblocked inventory management tag is attached is removed from theproximity of the master tag 130 or if another master tag blocks theinventory management tag from responding to further reads from themaster tag 130. This blocking of the inventory management tag couldoccur if the other master tag had the identifier of the inventorymanagement tag within its inventory record. With reference to thenon-limiting example depicted in FIG. 9, if the inventory management taghaving the identifier D5 is in the proximity of the master tag 130, butnot actually present on the pallet 110, the inventory management taghaving the identifier D5 may stop responding to further requests forinventory management tag data when it is removed from the proximity ofthe master tag 130 or blocked by a master tag associated with itspallet. In some non-limiting embodiments, the identifier of theinventory management tag may be deleted from the tag data record 320 ifthe tag stops responding to the further requests for inventorymanagement tag data.

At step 550 within FIG. 11, the inventory management tag data present inthe tag data record 320 can be transmitted as described previously.However, in some non-limiting embodiments, the contents of the inventoryrecord 910 may also be transmitted, in a similar manner. The inventorymanagement tag data present in the tag data record 320 and the contentsof the inventory record 910 may be received at the reader 140, andtransmitted to the inventory management entity 150. The inventorymanagement entity 150 may be configured to sort and compare theinventory management tag data present in the tag data record 320 and thecontents of the inventory record 910, for billing and/or inventorypurposes, as well as other inventory management purposes listed above.

In other non-limiting embodiments, the inventory management tag datapresent in the tag data record 320 may be transmitted at step 550, alongwith additional data which indicates the status of the identifier D1,D2, D3, D4, in relation to the inventory record 910. For instance, themaster tag 130 may transmit the contents of the tag data record 320,along with an indicator as to whether or not an identifier present inthe tag data record 320 is present or absent in the inventory record910. In a non-limiting example, with reference to the embodimentdepicted in FIG. 9, the identifier D5 would be transmitted with anidentifier indicating that it is absent from the inventory record 910,while the identifiers D1, D2, D3, D4 would be transmitted with anidentifier indicating they are present in the inventory record 910.

In yet other non-limiting embodiments, the contents of the tag datarecord 320 may be transmitted at step 550, along with the identifierspresent in the inventory record 910 that are not present in the tag datarecord 320. In these non-limiting embodiments, the identifiers presentin the inventory record 910, that are not present in the tag data record320 may be transmitted along with an indicator of this status. Forinstance, with reference to the non-limiting example depicted in FIG.10, the identifier D4 would be transmitted with an identifier indicatingthat it is absent from the tag data record 320. The inventory managemententity 150 may be configured to process this information for inventoryaccounting purposes, as well as other inventory management purposeslisted above. For example, billing for the goods on the pallet couldproceed, excluding the goods associated with the identifier D4, which isabsent from the tag data record 320, Further, the inventory managemententity 150 may be able to locate the inventory management tag with theidentifier D4 on another pallet.

In yet other non-limiting embodiments, a copy of the inventory record910 may be accessible to the inventory management entity 150 at adatabase (not depicted) which links master tag identifiers, such as themaster tag identifier stored at record 310, with copies of inventoryrecords, such as the inventory record 910. In these non-limitingembodiments, the processing unit 136 may compare the inventory record910 with the tag data record 320. Based on this comparison, at step 550,the master tag 130 may transmit the master tag identifier within therecord 310 along with any “missing” identifiers that are present in theinventory record 910 but that are not present in the tag data record 320(e.g. FIG. 10) and/or any “extra” identifiers that are present in thetag data record 320 but that are not present in the inventory record 910(e.g. FIG. 9). In some embodiments, additional indicators may be sent toindicate the status of each identifier, as described above. In somenon-limiting examples such as FIG. 8, all of the identifiers which arepresent in the inventory record 910 may be present in the tag datarecord 320, and vice versa. In these embodiments, the master tag 130 maytransmit only the master tag identifier, thus indicating that allinventory is accounted for. Alternatively, the master tag 130 maytransmit the master tag identifier and an indicator indicating that allexpected inventory is present, and further no additional inventory ispresent.

Hence, in these non-limiting embodiments in which the processing unit136 compares the inventory record 910 to the tag data record 320, notall of the read identifiers need to be transmitted to the reader 140 andthe content of the master tag response signal 144 may be reduced. Thiscan reduce the time required for the reader to receive the masterresponse signal 144 significantly.

In these non-limiting embodiments, the inventory management entity 150is configured to receive the data indicating the presence of additionalinventory or the absence of expected inventory, along with the mastertag identifier. The inventory management entity 150 can then utilize themaster tag identifier to look-up the corresponding inventory record 910and compare the received information to the inventory record 910, forbilling and/or inventory purposes, as well as other inventory managementpurposes listed above.

In some non-limiting embodiments, the master tag 130 may be configuredto exchange tag data stored in the memory unit 138 with other mastertags, for example master tags attached to adjacent pallets, in order toobtain a more complete accounting of inventory. These embodiments willbe described below with reference to FIGS. 13 to 15.

A method for wireless inventory management according to non-limitingembodiments of the present invention is now described with reference toFIG. 12. In order to assist in the explanation of the method, it will beassumed that the method of FIG. 12 is operated using the system depictedin FIG. 5. The method depicted in FIG. 12 is substantially similar tothe method depicted in FIG. 11, with like steps represented by likenumbers. However, the method depicted in FIG. 12 further comprises astep 1355 in which the master tag 130 is configured to determine if thereader 140 from which an inventory tag data request has been received,at step 540, is a destination reader. In a non-limiting embodiment, thestep 1355 is executable within the processing unit 136.

In some non-limiting embodiments, as the pallet 110 is shipped from onelocation to another location, the master tag 130 may enter into theproximity of more than one reader 140. In a non-limiting example, ashipment of goods may be loaded onto a pallet 110 at a warehouse. Thepallet 110 may be loaded onto a transport vehicle, and transported to acentral inventory warehouse. If an order is placed by a customer, thepallet 110 may then be shipped via another transport vehicle to acustomer warehouse for storage. The customer may yet further ship thepallet 110, via yet another transport vehicle to a customer store, wherethe shipment is unloaded from the pallet 110. In this example, a reader140, or a plurality of readers 140, may be present at each warehouse, oneach of the transport vehicles and at the customer store. It may bedesirable to continue to block the tags attached to the goods in theshipment, until the pallet 110 has reached its destination.

Hence, at step 1355, the processing unit 136 determines if the reader140 from which the tag data read request has been received, is a readerlocated at a final destination. This determination may comprisereceiving an indicator from the reader 140 as to whether it is thedestination reader. In some embodiments, this indicator may be presentin the read signal 143 received at the master tag 130. However, in otherembodiments, this indicator may also be transmitted to the master tag130 via a destination signal 610 transmitted by the reader 140. In thesenon-limiting embodiments, the reader 140 is configured to transmit thedestination signal 610. In alternative non-limiting embodiments, themaster tag 130 may store a destination reader identifier within thememory unit 138. In this case, the processing unit 136 may be configuredto determine if the reader 140 is the reader located at the finaldestination by comparing a reader identifier received from the reader140 with the stored destination reader identifier.

If the processing unit 136 determines the reader 140 is a destinationreader, the tags are unblocked at step 755, as described above. However,if the processing unit 136 determines the reader 140 is not adestination reader, the master tag does not unblock the inventorymanagement tags and may continue to request tag data at step 510.

Returning to FIG. 2, and with reference to FIGS. 8, 9 and 10, in someembodiments of the present invention where the inventory management tagsmay not be blocked, the memory unit 138 of the master tag 130 may alsoinclude an inventory record 910, as described above. Hence, byprocessing the data stored at the tag data record 320 and the inventoryrecord 910, the processing unit 136 may determine identifiers of theplurality of inventory management tags 120 a, 120 b, 120 c, 120 d whichare present in one record but not the other. As described above, inthese non-limiting embodiments, the master response signal 143 maycomprise only the identifiers of the plurality of inventory managementtags 120 a, 120 b, 120 c, 120 d which are present in one record but notthe other (.i.e. the missing and/or extra identifiers).

Turning now to FIG. 13, in some embodiments of the present invention, ashipment of goods may be loaded onto a plurality of pallets 1410 a, 1410b, 1410 c, each similar to the pallet 110 of FIG. 1. The plurality ofpallets 1410 a, 1410 b, 1410 c may be shipped together in a container(not depicted) to a destination.

Within these embodiments, a respective master tag 1430 a, 1430 b, 1430 cis attached to each of the plurality of pallets 1410 a, 1410 b, 1410 c,respectively in a similar manner to the attachment of the master tag 130to pallet 110, as described above. Each of the plurality of pallets 1410a, 1410 b, 1410 c will further comprise a plurality of inventorymanagement tags 1420, similar to the plurality of inventory managementtags 120 a, 120 b, 120 c, 120 d, described above, each of the inventorymanagement tags 1420 is attached to goods loaded onto each of theplurality of pallets 1410 a, 1410 b, 1410 c.

Each of the inventory management tags 1420 comprise an identifierassociated with the item to which the inventory management tag 1420 isattached, as described above. In the example depicted in FIG. 13, thepallet 1410 a comprises inventory management tags 1420 with identifiersD1 a, D2 a, D3 a, D4 a. The pallet 1410 b comprises inventory managementtags 1420 with identifiers D1 b, D2 b, D3 b, D4 b. The pallet 1410 ccomprises inventory management tags 1420 with identifiers D1 c, D2 c, D3c, D4 c.

Within the example depicted in FIG. 13, the plurality of pallets 1410 a,1410 b, 1410 c are depicted as being adjacent to one another; however,the arrangement of the plurality of pallets 1410 a, 1410 b, 1410 c isnot particularly limited. For example, the plurality of pallets 1410 a,1410 b, 1410 c may be stacked, arranged side by side, etc.

Each of the master tags 1430 a, 1430 b, 1430 c may be similar toembodiments of the master tag 130 described with reference to the FIG.1, 2, 5, or 7. Hence, each master tag 1430 a, 1430 b, 1430 c comprisesthe tag communication unit 132, the reader communication unit 134, or insome embodiments the communication unit 133, the processing unit 136,and the power source 139, of the master tag 130, with functionality asdescribed above. In some non-limiting embodiments, each of the mastertags 1430 a, 1430 b, 1430 c may further comprise the blocker unit 610,with functionality as described above. In some other non-limitingembodiments, each of the pallets 1410 a, 1410 b, 1410 c may furthercomprise the blocker tag 810, with functionality as described above,

Each of the master tags 1430 a, 1430 b, 1430 c further comprises amemory unit 1438 a, 1438 b, 1438 c, respectively, for which non-limitingexamples are depicted in FIG. 14. Within the non-limiting examplesdepicted in FIG. 14, each memory unit 1438 a, 1438 b, 1438 c comprises arespective tag data record 1520 a, 1520 b, 1520 c, a respectiveinventory record 1530 a, 1530 b, 1530 c, and a respective master tag IDrecord 1540 a, 1540 b, 1540 c, similar to the tag data record 320, theinventory record 910, and the master tag ID record 310 of the memoryunit 138 depicted in FIG. 8.

The master tag ID records 1540 a, 1540 b, 1540 c comprise a field forstoring an identifier of each master tag 1430 a, 1430 b, 1430 c. In theexample depicted, the identifiers of each master tag 1430 a, 1430 b,1430 c comprise identifiers A1, B2 and C3, respectively. The tag datarecords 1520 a, 1520 b, 1520 c comprise a plurality of fields forstoring inventory management tag identifiers which have been retrievedfrom inventory management tags 1420, in a manner similar to thatdescribed above.

The inventory records 1530 a, 1530 b, 1530 c comprise a plurality offields for storing the inventory management tag identifiers which areexpected to be present on each pallet 1410 a, 1410 b, 1410 c. Theinventory records 1530 a, 1530 b, 1530 c may be provisioned in a mannersimilar to the provisioning of inventory record 910, described above.

As depicted in the non-limiting examples of FIG. 14, there arediscrepancies between the tag data records 1520 a, 1520 b, 1520 c andthe inventory records 1530 a, 1530 b, 1530 c of each memory unit 1438 a,1438 b, 1438 c. These discrepancies may be due to the configuration ofeach master tag 1430 a, 1430 b, 1430 c and/or the configuration of thegoods on each pallet 1410 a, 1410 b, 1410 c. In any event, the mastertag 1430 a, 1430 b, 1430 c may be unable to retrieve data from certaininventory management tags attached to the goods.

In some non-limiting embodiments, these discrepancies may be resolvedonce the data present on the memory units 1438 a, 1438 b, 1438 c of eachof the master tags 1430 a, 1430 b, 1430 c is retrieved by the reader140, and received by the inventory management entity 150 of FIG. 1.Either the inventory management entity 150 or the reader 140 couldconsolidate the information to properly analyse the inventory on thepallets 1410 a, 1410 b, 1410 b, 1410 c. In other non-limitingembodiments, resolution of all discrepancies at the inventory managementunit 150 and/or the reader 140 may not be possible and/or desirable. Insome instances, the pallets 1410 a, 1410 b, 1410 c may be separated andshipped to different locations once the shipment has reached anintermediate destination and a reader (similar to the reader 140) maynot be present at the intermediate destination that is capable toretrieve the data and resolve the discrepancies. In this case, the datafrom each master tag 1430 a, 1430 b, 1430 c may be processed bydifferent inventory management entities, each belonging to differentorganizations, or processed for different accounts within a singleinventory management entity. The discrepancies may then lead to anincorrect assessment of inventory, and errors in billing. In otherinstances, the inventory management entity and/or the readers may nothave the functionality to clear up the discrepancies in the accountingof inventory.

In order to resolve the discrepancies, in some non-limiting embodimentsof the present invention, each of the master tags 1430 a, 1430 b, 1430 cis further configured to communicate with at least one of of the othermaster tags 1430 a, 1430 b, 1430 c, via the tag communication unit 132,the reader communication unit 134 or the communication unit 133.Specifically, each master tag 1430 a, 1430 b, 1430 c is configured totransmit inventory management tag data or processed versions of theinventory management tag data to at least one other of the master tags1430 a, 1430 b, 1430 c.

In one non-limiting embodiment, as depicted in FIG. 13, each of themaster tags 1430 a, 1430 b, 1430 c is configured to transmit a signal1415 a, 1415 b, 1415 c, respectively. Each of the signals 1415 a, 1415b, 1415 c comprise inventory management tag data derived from at leastthe tag data records 1520 a, 1520 b, 1520 c within the memory units 1438a, 1438 b, 1438 c, respectively. In some embodiments, each of thesignals 1415 a, 1415 b, 1415 c may be transmitted to all of the mastertags 1430 a, 1430 b, 1430 c. In other embodiments, each of the signals1415 a, 1415 b, 1415 c may be transmitted to an adjacent master tag. Inone non-limiting example, the master tag 1430 a may transmit the signal1415 a which may be received only at master tag 1430 b. In onenon-limiting example, this may be achieved by limiting the strength ofthe signal 1430 a, such that it is received only at the master tag 1430b. In other embodiments, the tag communication unit 132, the readercommunication unit 134 and/or the communication unit 133 at the mastertag 1430 a may be configured to transmit the signal 1430 a in thedirection of the master tag 1430 b.

In other non-limiting embodiments, each of the signals 1415 a, 1415 b,1415 c may be intended for a specific master tag. In these embodiments,each of the memory units 1438 a, 1438 b, 1438 c may further comprise arecord of the identifiers of the master tags 1430 a, 1430 b, 1430 c inthe shipment of goods. In these embodiments, each of the signals 1415 a,1415 b, 1415 c may further comprise the identifier of the master tag1430 a, 1430 b, 1430 c for which each of the signals 1415 a, 1415 b,1415 c is intended. In a non-limiting example, each of the master tags1430 b, 1430 c may be configured to receive the signal 1415 a, andprocess the signal 1415 a only if the signal 1415 a contains theidentifier of the master tag 1430 b or 1430 c respectively. Transmissionof the signals 1415 b and 1415 c may be configured in a similar manner.

In embodiments where the signals 1415 a, 1415 b, 1415 c are transmittedto an adjacent master tag or the signals 1415 a, 1415 b, 1415 c areintended for a specific master tag, the master tag which receives thesignal may be further configured to extract the data within the signal1415 a, 1415 b, 1415 c and transmit the data to one or more other mastertags. In a non-limiting example, the master tag 1430 a may transmit thesignal 1415 a to the master tag 1430 b. The master tag 1430 b mayextract the data from the signal 1415 a and transmit the signal 1415 bto the master tag 1430 c. The signal 1415 b may comprise the dataextracted from the signal 1415 a and data contained in the memory unit1438 b. In this manner, data may be passed from master tag to master tagwithout the signals 1415 a, 1415 b, 1415 c being available to all of themaster tags 1430 a, 1430 b, 1430 c.

In some non-limiting embodiments, the signals 1415 a, 1415 b, 1415 c maycomprise inventory data derived from the tag data records 1520 a, 1520b, 1520 c and the inventory records 1530 a, 1530 b, 1530 c, within thememory units 1438 a, 1438 b, 1438 c, respectively. In the non-limitingexample depicted in FIG. 13, each signal 1415 a, 1415 b, 1415 ccomprises the identifiers of inventory management tags which are presentin one record (for example, the tag data records 1520 a, 1520 b, 1520 c)but not the other record (for example, the inventory records 1530 a,1530 b, 1530 c) and vice versa. Furthermore, each identifier is furtherclassified either as being “Missing” from the tag data record 1520 a,1520 b, 1520 c, but present in the respective inventory record 1530 a,1530 b, 1530 c, or as being “Extra”, indicating that the identifier ispresent in the tag data record 1520 a, 1520 b, 1520 c, but not presentin the respective inventory record 1530 a, 1530 b, 1530 c. In thenon-limiting example of FIG. 13, each of the signals 1415 a, 1415 b,1415 c further comprise the master tag identifier as recorded in themaster tag ID records 1540 a, 1540 b, 1540 c. A classification of“Missing” may indicate that the inventory management tag associated withthe “Missing” identifier was not readable by the master tag attached tothe pallet where the inventory management tag is located. Aclassification of “Extra” may indicate that an inventory management taglocated on an adjacent pallet was read by the master management tag.

Within the example depicted in FIG. 13, the signal 1415 a comprises themaster tag identifier A1 corresponding to the master tag 1410 a and theidentifier D4 a which is “missing” from the tag data record 1520 a, butpresent in the inventory record 1530 a of the memory unit 1438 a.Similarly, the signal 1415 b comprises the master tag identifier B2corresponding to the master tag 1410 b and the identifier D4 a and D4 cwhich are “extra”, indicating they are present in the tag data record1520 b, but not in the inventory record 1530 b of the memory unit 1438b. And similarly, the signal 1415 c comprises the master tag identifierC3 corresponding to the master tag 1410 c and the identifier D4 b whichis present in the tag data record 1520 c, but not in the inventoryrecord 1530 c of the memory unit 1438 c.

Each of the signals 1410 a, 1410 b, 1410 c may be received at each ofthe master tags 1430 a, 1430 b, 1430 c, where they are processed by therespective processing units 136. In one non-limiting example, the signal1415 b is received at the master tag 1430 a, where the processing unit136 compares the contents of the signal 1415 b to the contents of theinventory record 1530 a and/or the tag data record 1520 a of the memoryunit 1438 a. The processing unit 136 is configured to recognize that ofthe “extra” identifiers present in the signal 1415 b, the identifier D4a is present in the inventory record 1530 a of the memory unit 1438 a.The tag data record 1520 a of the memory unit 1438 a is then updated toreflect the presence of the inventory management tag associated with theidentifier D4 a. Within the tag data record 1520 a, in some non-limitingembodiments, the identifier D4 a may be highlighted/flagged as asecondary read, i.e. a read from another master tag, rather than as adirect read, i.e. read by the master tag 1430 a. The inventorymanagement entity 150 may treat secondary read results differently forsome purposes, for example inventory accounting and/or billing purposes,as well as other inventory management purposes listed above.

In order to eliminate a double counting of the identifier D4 a, in someembodiments, the processing unit 136 at the master tag 1430 b may deletethe identifier D4 a from the tag data record 1520 b at the memory unit1438 b once the signal 1415 b has been transmitted. In othernon-limiting embodiments, the master tag 1430 a may transmit a signal1412 a configured to indicate to the master tag 1430 b that theidentifier D4 a has been received. In response to receiving the signal1412 a, the processing unit 136 at the master tag 1430 b may delete theidentifier D4 a from the tag data record 1520 b at the memory unit 1438b.

In yet other embodiments, the identifier D4 a is not deleted from thetag data record 1520 b at the memory unit 1438 b, and the discrepancy ismanaged by the inventory management entity 150 of FIG. 1, once the tagdata has been retrieved from the master tags 1430 a and 1430 b by thereader 140.

In another non-limiting example, the signal 1415 b may be received atthe master tag 1430 c, where the processing unit 136 of the master tag1430 c compares the contents of the signal 1415 b to the contents of theinventory record 1530 c and/or the tag data record 1520 c of the memoryunit 1438 c. The processing unit 136 is configured to recognize that, ofthe “extra” identifiers present in the signal 1415 b, the identifier D4c, is present in the inventory record 1530 c of the memory unit 1438 c.As the identifier D4 c is already present in the tag data record 1420 cof the memory unit 1438 c, in one non-limiting embodiment, no action istaken.

In yet another non-limiting example, the signal 1415 a may be receivedat the master tag 1430 b, where the processing unit 136 of the mastertag 1430 b compares the contents of the signal 1415 a to the contents ofthe inventory record 1530 b and/or the tag data record 1520 b of thememory unit 1438 b. The processing unit 136 is configured to recognizethat the “missing” identifier D4 a present in the signal 1415 a ispresent in the tag data record 1520 b of the memory unit 1438 b. Withinthis embodiment, the master tag 1430 b may be configured to transmit asignal 1412 b configured to indicate to the master tag 1430 a that theidentifier D4 a is present in the tag data record 1520 b of the memoryunit 1438 b. Within this example, the accounting for the identifier D4 ain the tag data record 1520 a of the memory unit 1438 a can be completedas described above.

In yet another non-limiting example, the signal 1415 c may be receivedat the master tag 1430 b, where the processing unit 136 of the mastertag 1430 b compares the contents of the signal 1415 c to the contents ofthe inventory record 1530 b and/or the tag data record 1520 b of thememory unit 1438 b. The processing unit 136 is configured to recognizethat the “extra” identifier D4 b present in the signal 1415 c, is alsopresent in the inventory record 1530 b of the memory unit 1438 b.However, this is similar to the example described above with referenceto the identifier D4 c and can be addressed in a similar manner.

In another non-limiting example, the signal 1415 c is received at themaster tag 1430 a, where the processing unit 136 of the master tag 1430a compares the contents of the signal 1415 c to the contents of theinventory record 1530 a and/or the tag data record 1520 a of the memoryunit 1438 a. The processing unit 136 is configured to recognize that the“extra” identifier D4 b present in the signal 1415 c, is not present inthe inventory record 1530 a of the memory unit 1438 a, and no action istaken. I

n another non-limiting example, the signal 1415 a is received at themaster tag 1430 c where the processing unit 136 of the master tag 1430 ccompares the contents of the signal 1415 a to the contents of theinventory record 1530 c and/or the tag data record 1520 c of the memoryunit 1438 c. The processing unit 136 is configured to recognize that the“missing” identifier D4 a present in the signal 1415 a, is not presentin the tag data record 1520 c of the memory unit 1438 c, and no actionis taken.

FIG. 15 depicts further non-limiting examples of the memory units 1438a, 1438 b, 1438 c of FIG. 14 once the various exchanges of signals arecompleted. As described above, after the exchange of signals arecomplete, “missing” identifiers may have been located by another mastertag and “extra” identifiers may have been deleted. In other embodiments,the “extra” identifiers remain within their respective tag data recordsand the “missing” identifiers that have been located by a secondarymaster tag, may be flagged to this effect as described above.

There are many alternatives for the signals 1415 a, 1415 b, 1415 ccontemplated. In some non-limiting embodiments, the signals 1415 a, 1415b, 1415 c comprise the full contents of the tag data records 1520 a,1520 b, 1520 c present at each of the master tags 1430 a, 1430 b, 1430c, respectively. In this case, the processing unit 136 of each of themaster tags 1430 a, 1430 b, 1430 c that receives the signals 1415 a,1415 b, 1415 c is configured to filter through the contents to identifyif any “missing” identifiers from their inventory records can belocated. In other non-limiting embodiments, the signals 1415 a, 1415 b,1415 c comprise the full contents of the tag data records 1520 a, 1520b, 1520 c, respectively and the inventory records 1530 a, 1530 b, 1530c, respectively. In these embodiments, the processing unit 136 of eachof the master tags 1430 a, 1430 b, 1430 c is configured to compare thedata received and update their respective tag data record 1520 a, 1520b, 1520 c as described above. Further, the processing unit 136 in thiscase may transmit a return signal, such as signal 1412 b describedabove, to the master tag that transmitted the signal 1415 a, 1415 b,1415 c if there is an identifier within the received inventory recordthat matches an identifier within the tag data record stored in itsmemory unit. The master tag that transmitted the signal 1415 a, 1415 b,1415 c may or may not have already read the inventory management tagidentifier and therefore, it may or may not actually be “missing”. Inother non-limiting embodiments, the signals 1415 a, 1415 b, 11415 ccomprise the full contents of the inventory records 1530 a, 1530 b, 1530c respectively. In these embodiments, the processing unit of each of themaster tags 1430 a, 1430 b, 1430 c is configured to compare the datareceived and determine if any identifiers match identifiers within theirrespective tag data records 1520 a, 1520 b, 1520 c. As a result of thiscomparison, the processing unit 136 can transmit a signal similar tosignal 1412 b described above indicating which identifiers that are onanother master tag that it had read. In yet further non-limitingembodiments, the signals 1415 a, 1415 b, 1415 c could comprise only the“missing” identifiers or only the “extra” identifiers. Further, in somecases described above, the signals 1415 a, 1415 b, 1415 c may notrequire the master tag identifier to be transmitted.

In some non-limiting embodiments, the tag data records 1520 a, 1520 b,1520 c and/or the inventory records 1530 a, 1530 b, 1530 c of each ofthe master tags 1430 a, 1430 b, 1430 c, may be further stored at thememory units 1438 a, 1438 b, 1438 c of the other master tags 1430 a,1430 b, 1430 c. In this manner, data retrieved by the reader 140 fromany of the master tags 1430 a, 1430 b, 1430 c in the shipment of goodsmay convey the complete inventory of the shipment.

Although the transmissions between the master tags 1430 a, 1430 b, 1430c were described as proceeding directly, in alternative embodiments ofthe present invention, the signals 1415 a, 1415 b, 1415 c could betransmitted between the other master tags 1430 a, 1430 b, 1430 c via thereader 140. In this case, the reader 140 acts as a hub forcommunications between the master tags 1430 a, 1430 b, 1430 c. This maybe particularly applicable in cases where the master tags 1430 a, 1430b, 1430 c are unable to communicate with each other due to distance,attenuation, transmission power or communication standards.

Although the embodiments of the present invention described above withreference to FIGS. 1 to 15 are directed to inventory management withinpallets, as discussed previously this should not limit the scope of thepresent invention. For instance, the transport object in which theembodiments of the master tag described above can be applied is notlimited to pallets and could further apply to a shipping container, atruck trailer, a train car, a case, a storage container, a box, etc.Further, the embodiments of the master tags described above may beapplied to non-transport objects such as goods that are located togethersuch as in consumer displays, on shelves, in warehouses, in factories,in manufacturing facilities, on shop floors, or in storage rooms, etc.Yet further, the embodiments of the master tags described above may beapplied to non-inventory articles, such as assets. In that case, themanagement system of the above described embodiments would relate to anasset management system. Based on the above discussion, it should beunderstood that the master tag 130 described in the present inventionmay apply as a master pallet tag, a master container tag, a mastervehicle tag, a master trailer tag, a master case tag, a master box tag,a master shelf tag, a master display tag, a master factory tag, a masterroom tag, a master asset tag etc. Other applications for the master tag130 may be contemplated by one of skill in the art after reading thedescription of the present invention.

Although described above as an inventory record, it should be understoodthat more generally the record can be considered an article record. Inthis case, the record may comprise identifiers associated with inventoryelements and/or asset elements.

Those skilled in the art will appreciate that certain functionality ofthe master tag 130, the reader 140, inventory management entity 150and/or other elements of the infrastructure described herein may beimplemented as pre-programmed hardware or firmware elements (e.g.,application specific integrated circuits (ASICs), electrically erasableprogrammable read-only memories (EEPROMs), etc.), or other relatedcomponents. In other embodiments, certain portions of the master tag130, the reader 140, the inventory management entity 150 and/or otherelements may be implemented as an arithmetic and logic unit (ALU) havingaccess to a code memory (not shown) which stores program instructionsfor the operation of the ALU. The program instructions could be storedon a medium which is fixed, tangible and readable directly by the mastertag 130, the reader 140, the inventory management entity 150 and/orother elements, (e.g., removable diskette, CD-ROM, ROM, fixed disk, USBdrive), or the program instructions could be stored remotely buttransmittable to the master tag 130, the reader 140, the inventorymanagement entity 150 and/or other elements via a modem or otherinterface device.

Persons skilled in the art will appreciate that there are yet morealternative implementations and modifications possible for implementingthe present invention, and that the above implementations and examplesare only illustrations of one or more embodiments of the presentinvention. The scope of the invention, therefore, is only to be limitedby the claims appended hereto.

1. A method implemented by a master RFID tag, the method comprising:transmitting at least one first RFID read signal to a plurality of RFIDtags local to the master RFID tag; receiving a first RFID responsesignal from each of the plurality of RFID tags in response to the atleast one first RFID read signal, each of the first RFID responsesignals comprising an identifier associated with an article; maintainingan article record indicating at least one expected article that is to bemanaged by the master RFID tag; identifying one or more extra articlesby identifying a specific identifier received within the plurality offirst RFID response signals that lacks a corresponding specific expectedarticle within the article record; and transmitting a master signalcomprising one or more identifiers of the extra articles.
 2. A methoddefined in claim 1 further comprising identifying one or more missingarticles by identifying a specific expected article within the articlerecord that lacks a corresponding specific identifier received withinthe plurality of first RFID response signals, the master signal furthercomprising one or more identifiers of the missing articles.
 3. A methoddefined in claim 1, wherein the transmitting a master signal comprises,responsive to receipt of a second RFID read signal from an RFID reader,transmitting a second RFID response signal, the second RFID responsesignal comprising the one or more identifiers of the extra articles. 4.A method defined in claim 1, the master RFID tag being a first masterRFID tag, wherein the transmitting a master signal comprisestransmitting a master signal comprising the one or more identifiers ofthe extra articles to a second master RFID tag.
 5. A method defined inclaim 4 further comprising maintaining a second article record withinthe second master RFID tag for indicating at least one expected articlethat is to be managed by the second master RFID tag; and receiving arequest signal comprising at least one identifier from the secondarticle record from the second master RFID tag; and wherein thetransmitting a master signal is responsive to the request signal.
 6. Amethod defined in claim 5, wherein the transmitting the master signal tothe second master RFID tag occurs if the at least one identifier fromthe second article record within the request signal is one of theidentifiers of the extra articles.
 7. A method implemented by a masterRFID tag, the method comprising: transmitting at least one first RFIDread signal to a plurality of RFID tags local to the master RFID tag;receiving a first RFID response signal from each of the plurality ofRFID tags in response to the at least one first RFID read signal, eachof the first RFID response signals comprising an identifier associatedwith an article; maintaining an article record indicating at least oneexpected article that is to be managed by the master RFID tag;identifying one or more missing articles by identifying a specificexpected article within the article record that lacks a correspondingspecific identifier received within the plurality of first RFID responsesignals; and transmitting a master signal comprising one or moreidentifiers of the missing articles.
 8. A method defined in claim 7,wherein the transmitting a master signal comprises, responsive toreceipt of a second RFID read signal from an RFID reader, transmitting asecond RFID response signal, the second RFID response signal comprisingthe one or more identifiers of the missing articles.
 9. A method definedin claim 7, the master RFID tag being a first master RFID tag, whereinthe transmitting a master signal comprises transmitting a master signalcomprising the one or more identifiers of the missing articles to asecond master RFID tag.
 10. A method defined in claim 7, the master RFIDtag being a first master RFID tag and the identifiers received withinthe first RFID response signals being a first set of identifiers; themethod further comprising receiving data associated with a second set ofidentifiers from a second master RFID tag and comparing the second setof identifiers with the one or more identifiers of the missing articles.11. A method defined in claim 10 further comprising transmitting arequest signal comprising the one or more identifiers of the missingarticles to the second master RFID tag prior to receiving dataassociated with a second set of identifiers from the second master RFIDtag.
 12. A master RFID tag comprising: a first communication unitoperative for: transmitting at least one first RFID read signal to aplurality of RFID tags local to the master RFID tag; and receiving afirst RFID response signal from each of the plurality of RFID tags inresponse to the at least one first RFID read signal, each of the firstRFID response signals comprising an identifier associated with anarticle; a memory unit operative for storing an article recordindicating at least one expected article that is to be managed by themaster RFID tag; a processing unit operative for at least one of:identifying one or more extra articles by identifying a specificidentifier received within the plurality of first RFID response signalsthat lacks a corresponding specific expected article within the articlerecord; and identifying one or more missing articles by identifying aspecific expected article within the article record that lacks acorresponding specific identifier received within the plurality of firstRFID response signals; and a second communication unit operative fortransmitting a master signal comprising at least one of: one or moreidentifiers of the extra articles and one or more identifiers of themissing articles.
 13. A master RFID tag defined in claim 12, wherein theprocessing unit is operative for identifying one or more extra articlesand the master signal comprises one or more identifiers of the extraarticles.
 14. A master RFID tag defined in claim 12, wherein theprocessing unit is operative for identifying one or more missingarticles and the master signal comprises one or more identifiers of themissing articles.
 15. A master RFID tag defined in claim 12, wherein totransmit a master signal, the second communication unit is operativefor, responsive to receipt of a second RFID read signal from an RFIDreader, transmitting a second RFID response signal, the second RFIDresponse signal comprising at least one of: the one or more identifiersof the extra articles and the one or more identifiers of the missingarticles.
 16. A master RFID tag defined in claim 12, the master RFID tagbeing a first master RFID tag, wherein to transmit a master signal, thesecond communication unit is operative for transmitting a master signalcomprising at least one of: the one or more identifiers of the extraarticles and the one or more identifiers of the missing articles to asecond master RFID tag.
 17. A master RFID tag defined in claim 16,wherein the second master RFID tag is operative for maintaining a secondarticle record for indicating at least one expected article that is tobe managed by the second master RFID tag; wherein the secondcommunication unit is further operative for receiving a request signalcomprising at least one identifier from the second article record fromthe second master RFID tag; and wherein the transmitting a master signalis responsive to the request signal.
 18. A master RFID tag defined inclaim 17, wherein the second communication unit is operative fortransmitting the master signal to the second master RFID tag if the atleast one identifier from the second article record within the requestsignal is one of the identifiers of the extra articles.
 19. A masterRFID tag defined in claim 12, the master RFID tag being a first masterRFID tag and the identifiers received within the first RFID responsesignals being a first set of identifiers; wherein one of the first andsecond communication units is further operative for receiving dataassociated with a second set of identifiers from a second master RFIDtag; and wherein the processing unit is further operative for comparingthe second set of identifiers with the one or more identifiers of themissing articles.
 20. A master RFID tag defined in claim 19, wherein theone of the first and second communication units is further operative fortransmitting a request signal comprising the one or more identifiers ofthe missing articles to the second master RFID tag prior to receivingdata associated with a second set of identifiers from the second masterRFID tag.